LIDAR with co-aligned transmit and receive paths

ABSTRACT

One example system includes a light source that emits light. The system also includes a waveguide that guides the emitted light from a first side of the waveguide toward a second side of the waveguide opposite the first side. The waveguide has a third side extending between the first side and the second side. The system also includes a mirror that reflects the guided light toward the third side of the waveguide. At least a portion of the reflected light propagates out of the waveguide toward a scene. The system also includes a light detector, and a lens that focuses light from the scene toward the waveguide and the light detector.

BACKGROUND

Unless otherwise indicated herein, the materials described in thissection are not prior art to the claims in this application and are notadmitted to be prior art by inclusion in this section.

Light detectors, such as photodiodes, single photon avalanche diodes(SPADs), or other types of avalanche photodiodes (APDs), can be used todetect light that is imparted on their surfaces (e.g., by outputting anelectrical signal, such as a voltage or a current, that indicates anintensity of the light). Many types of such devices are fabricated outof semiconducting materials, such as silicon. In order to detect lightover a large geometric area, multiple light detectors can be arranged asan array. These arrays are sometimes referred to as siliconphotomultipliers (SiPMs) or multi-pixel photon counters (MPPCs).

Some of the above arrangements are sensitive to relatively lowintensities of light, thereby enhancing their detection qualities.However, this can lead to the above arrangements also beingdisproportionately susceptible to adverse background effects (e.g.,extraneous light from outside sources could affect a measurement by thelight detectors).

SUMMARY

In one example, a system comprises a light source that emits light. Thesystem also comprises a waveguide that guides the emitted light from afirst side of the waveguide to a second side of the waveguide oppositethe first side. The waveguide has a third side extending between thefirst side and the second side. The system also comprises a mirror thatreflects the guided light toward the third side of the waveguide. Atleast a portion of the reflected light propagates out of the waveguidetoward a scene. The system also comprises a light detector. The systemalso comprises a lens that focuses light from the scene toward thewaveguide and the light detector.

In another example, a system comprises a light source that emits light.The system also comprises a waveguide having an input end and one ormore output ends opposite the input end. The waveguide guides theemitted light from the input end to the one or more output ends. Thewaveguide has a given side that extends from the input end to the one ormore output ends. The system also comprises one or more mirrors thatreflect at least a portion of the guided light toward the given side ofthe waveguide. The reflected light propagates out of the waveguide. Thesystem also comprises a lens that directs, toward a scene, the reflectedlight propagating out of the waveguide. The system also comprises one ormore arrays of light detectors. The lens focuses light from the scenetoward the waveguide and the one or more arrays of light detectors.

In yet another example, method involves emitting light toward a firstside of a waveguide. The method also involves guiding, inside awaveguide, the emitted light from the first side to a second side of thewaveguide opposite the first side. The method also involves reflectingthe guided light toward a third side of the waveguide. At least portionof the reflected light propagates out of the third side of the waveguidetoward a scene. The method also involves focusing, via a lens, lightfrom the scene onto the waveguide and a light detector.

In still another example, a system comprises means for emitting lighttoward a first side of a waveguide. The system also comprises means forguiding, inside a waveguide, the emitted light from the first side to asecond side of the waveguide opposite the first side. The system alsocomprises means for reflecting the guided light toward a third side ofthe waveguide. At least portion of the reflected light propagates out ofthe third side of the waveguide toward a scene. The system alsocomprises means for focusing, via a lens, light from the scene onto thewaveguide and a light detector.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the figures and the followingdetailed description.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A is an illustration of a system that includes an aperture,according to example embodiments.

FIG. 1B is another illustration of the system of FIG. 1A.

FIG. 2A is a simplified block diagram of a LIDAR device, according toexample embodiments.

FIG. 2B illustrates a perspective view of the LIDAR device of FIG. 2A.

FIG. 3A is an illustration of a system that includes a waveguide,according to example embodiments.

FIG. 3B illustrates a cross-section view of the system of FIG. 3A.

FIG. 4A illustrates a first cross-section view of a system that includesmultiple waveguides, according to example embodiments.

FIG. 4B illustrates a second cross-section view of the system of FIG.4A.

FIG. 4C illustrates a third cross-section view of the system of FIG. 4A.

FIG. 4D illustrates a fourth cross-section view of the system of FIG.4A.

FIG. 5 illustrates a cross-section view of another system that includesa waveguide, according to example embodiments.

FIG. 6 illustrates a cross-section view of yet another system thatincludes a waveguide, according to example embodiments.

FIG. 7 is a flowchart of a method, according to example embodiments.

DETAILED DESCRIPTION

Any example embodiment or feature described herein is not necessarily tobe construed as preferred or advantageous over other embodiments orfeatures. The example embodiments described herein are not meant to belimiting. It will be readily understood that certain aspects of thedisclosed implementations can be arranged and combined in a wide varietyof different configurations. Furthermore, the particular arrangementsshown in the figures should not be viewed as limiting. It should beunderstood that other implementations might include more or less of eachelement shown in a given figure. In addition, some of the illustratedelements may be combined or omitted. Similarly, an exampleimplementation may include elements that are not illustrated in thefigures.

I. OVERVIEW

Example implementations may relate to devices, systems, and methods thatinvolve detecting light using one or more light detectors. In someexamples, the light detectors may be a sensing component of a lightdetection and ranging (LIDAR) device.

One example system includes a lens. The lens may be used to focus lightfrom a scene. However, the lens may also focus background light notintended to be observed by the system (e.g., sunlight). In order toselectively filter the light (i.e., separate background light from lightcorresponding to information within the scene), an opaque material(e.g., selectively etched metal, a glass substrate partially covered bya mask, etc.) may be placed behind the lens. The opaque material couldbe shaped as a slab, a sheet, or various other shapes in a variety ofembodiments. Within the opaque material, an aperture may be defined.With this arrangement, a portion of, or the entirety of, the lightfocused by the lens could be selected for transmission through theaperture.

In the direction of propagation of the light transmitted through theaperture, the system may include an array of light detectors (e.g.,SPADs, etc.) arranged to detect at least a portion of the focused lighttransmitted through the aperture.

The system may also include a light source that emits light, and awaveguide that receives the emitted light at an input end of thewaveguide. The waveguide guides the emitted light from the input end toan output end of the waveguide opposite the input end. The waveguide hasa given side that extends from the input end to the output end. Thewaveguide transmits at least a portion of the emitted light out of thegiven side and toward the lens. In general, the output end of thewaveguide may be positioned along a propagation path of the focusedlight propagating from the lens to the array of light detectors. In oneembodiment, the emitted light transmitted out of the waveguide maypropagate through the same aperture through which the focused light istransmitted toward the array of light detectors.

To facilitate propagation of the guided light out of the given side ofthe waveguide, in some examples, the system may include a mirrordisposed along a propagation path of the guided light propagating insidethe waveguide. The mirror may be tilted toward the given side of thewaveguide. As such, the mirror may reflect the guided light (or aportion thereof) toward a particular region of the given side that isco-aligned with the path of the focused light propagating toward thearray of light detectors. For example, the particular region may beadjacent to the aperture defined by the opaque material.

Thus, in one example arrangement, the system may illuminate the scene bydirecting the emitted light according to a transmit path that extendsthrough the waveguide, aperture, and lens. The system may also receivereflections of the emitted light from the illuminated scene according toa receive path that extends through the same lens and aperture. Thetransmit and receive paths of the light in this example could thus beco-aligned (e.g., associated with same or similar respectivefields-of-view).

Because the transmit path is spatially aligned with the receive path,the example system may reduce (or prevent) optical scanning distortionsassociated with parallax. For instance, if the transmit and receivepaths were instead to be spatially offset relative to one another (e.g.,have different respective viewing or pointing directions, etc.), ascanned representation of the scene could be affected by opticaldistortions such as parallax.

Other aspects, features, implementations, configurations, arrangements,and advantages are possible as well.

II. EXAMPLE SYSTEMS AND DEVICES

FIG. 1A is an illustration of a system 100 that includes an aperture,according to example embodiments. As shown, system 100 includes an array110 of light detectors (exemplified by detectors 112 and 114), anaperture 120 a defined within an opaque material 120, and a lens 130.System 100 may measure light 102 reflected or scattered by an object 198within a scene. In some instances, light 102 may also include lightpropagating directly from background sources (not shown) toward lens130. In some examples, system 100 may be included in a light detectionand ranging (LIDAR) device. For example, the LIDAR device may be usedfor navigation of an autonomous vehicle. Further, in some embodiments,system 100, or portions thereof, may be contained within an area that isunexposed to exterior light other than through lens 130. This may reducean amount of ambient light (which may affect measurements) reaching thedetectors in array 110.

Array 110 includes an arrangement of light detectors, exemplified bydetectors 112 and 114. In various embodiments, array 110 may havedifferent shapes. As shown, array 110 has a rectangular shape. However,in other embodiments, array 110 may be circular or may have a differentshape. The size of array 110 may be selected according to an expectedcross-sectional area of light 110 diverging from aperture 120 a. Forexample, the size of array 110 may be based on the distance betweenarray 110 and aperture 120 a, the distance between aperture 120 a andlens 130, dimensions of aperture 120 a, optical characteristics of lens130, among other factors. In some embodiments, array 110 may be movable.For example, the location of array 110 may be adjustable so as to becloser to, or further from, aperture 120 a. To that end, for instance,array 110 could be mounted on an electrical stage capable of translatingin one, two, or three dimensions.

Further, in some implementations, array 110 may provide one or moreoutputs to a computing device or logic circuitry. For example, amicroprocessor-equipped computing device may receive electrical signalsfrom array 110 which indicate an intensity of light 102 incident onarray 110. The computing device may then use the electrical signals todetermine information about object 198 (e.g., distance between object198 and system 100, etc.). In some embodiments, some or all of the lightdetectors within array 110 may be interconnected with one another inparallel. To that end, for example, array 110 may be a SiPM or an MPPC,depending on the particular arrangement and type of the light detectorswithin array 110. By connecting the light detectors in a parallelcircuit configuration, for instance, the outputs from the lightdetectors can be combined to effectively increase a detection area inwhich a photon in light 102 can be detected (e.g., shaded region ofarray 110 shown in FIG. 1A).

Light detectors 112, 114, etc., may include various types of lightdetectors. In one example, detectors 112, 114, etc., include SPADs.SPADs may employ avalanche breakdown within a reverse biased p-njunction (i.e., diode) to increase an output current for a givenincident illumination on the SPAD. Further, SPADs may be able togenerate multiple electron-hole pairs for a single incident photon. Inanother example, light detectors 112, 114, etc., may include linear-modeavalanche photodiodes (APDs). In some instances, APDs or SPADs may bebiased above an avalanche breakdown voltage. Such a biasing conditionmay create a positive feedback loop having a loop gain that is greaterthan one. Further, SPADs biased above the threshold avalanche breakdownvoltage may be single photon sensitive. In other examples, lightdetectors 112, 114, etc., may include photoresistors, charge-coupleddevices (CCDs), photovoltaic cells, and/or any other type of lightdetector.

In some implementations, array 110 may include more than one type oflight detector across the array. For example, array 110 can beconfigured to detect multiple predefined wavelengths of light 102. Tothat end, for instance, array 110 may comprise some SPADs that aresensitive to one range of wavelengths and other SPADs that are sensitiveto a different range of wavelengths. In some embodiments, lightdetectors 110 may be sensitive to wavelengths between 400 nm and 1.6 μm(visible and/or infrared wavelengths). Further, light detectors 110 mayhave various sizes and shapes within a given embodiment or acrossvarious embodiments. In some embodiments, light detectors 112, 114,etc., may include SPADs that have package sizes that are 1%, 0.1%, or0.01% of the area of array 110.

Opaque material 120 (e.g., mask, etc.) may block a portion of light 102from the scene (e.g., background light) that is focused by the lens 130from being transmitted to array 110. For example, opaque material 120may be configured to block certain background light that could adverselyaffect the accuracy of a measurement performed by array 110.Alternatively or additionally, opaque material 120 may block light inthe wavelength range detectable by detectors 112, 114, etc. In oneexample, opaque material 120 may block transmission by absorbing aportion of incident light. In another example, opaque material 120 mayblock transmission by reflecting a portion of incident light. Anon-exhaustive list of example implementations of opaque material 120includes an etched metal, a polymer substrate, a biaxially-orientedpolyethylene terephthalate (BoPET) sheet, or a glass overlaid with anopaque mask, among other possibilities. In some examples, opaquematerial 120, and therefore aperture 120 a, may be positioned at or neara focal plane of lens 130.

Aperture 120 a provides a port within opaque material 120 through whichlight 102 (or a portion thereof) may be transmitted. Aperture 120 a maybe defined within opaque material 120 in a variety of ways. In oneexample, opaque material 120 (e.g., metal, etc.) may be etched to defineaperture 120 a. In another example, opaque material 120 may beconfigured as a glass substrate overlaid with a mask, and the mask mayinclude a gap that defines aperture 120 a (e.g., via photolithography,etc.). In various embodiments, aperture 120 a may be partially or whollytransparent, at least to wavelengths of light that are detectable bylight detectors 112, 114, etc. For example, where opaque material 120 isa glass substrate overlaid with a mask, aperture 120 a may be defined asa portion of the glass substrate not covered by the mask, such thataperture 120 a is not completely hollow but rather made of glass. Thus,in some instances, aperture 120 a may be nearly, but not entirely,transparent to one or more wavelengths of light 102 (e.g., glasssubstrates are typically not 100% transparent). Alternatively, in someinstances, aperture 120 a may be formed as a hollow region of opaquematerial 120.

In some examples, aperture 120 a (in conjunction with opaque material120) may be configured to spatially filter light 102 from the scene atthe focal plane. To that end, for example, light 102 may be focused ontoa focal plane along a surface of opaque material 120, and aperture 120 amay allow only a portion of the focused light to be transmitted to array110. As such, aperture 120 a may behave as an optical pinhole. In oneembodiment, aperture 120 a may have a cross-sectional area of between0.02 mm² and 0.06 mm² (e.g., 0.04 mm²). In other embodiments, aperture120 a may have a different cross-sectional area depending on variousfactors such as optical characteristics of lens 130, distance to array110, noise rejection characteristics of the light detectors in array110, etc.

Thus, although the term “aperture” as used above with respect toaperture 120 a may describe a recess or hole in an opaque materialthrough which light may be transmitted, it is noted that the term“aperture” may include a broad array of optical features. In oneexample, as used throughout the description and claims, the term“aperture” may additionally encompass transparent or translucentstructures defined within an opaque material through which light can beat least partially transmitted. In another example, the term “aperture”may describe a structure that otherwise selectively limits the passageof light (e.g., through reflection or refraction), such as a mirrorsurrounded by an opaque material. In one example embodiment, mirrorarrays surrounded by an opaque material may be arranged to reflect lightin a certain direction, thereby defining a reflective portion, which maybe referred to as an “aperture”.

Although aperture 120 a is shown to have a rectangular shape, it isnoted that aperture 120 a can have a different shape, such as a roundshape, circular shape, elliptical shape, among others. In some examples,aperture 120 a can alternatively have an irregular shape specificallydesigned to account for optical aberrations within system 100. Forexample, a keyhole shaped aperture may assist in accounting for parallaxoccurring between an emitter (e.g., light source that emits light 102)and a receiver (e.g., lens 130 and array 110). The parallax may occur ifthe emitter and the receiver are not located at the same position, forexample. Other irregular aperture shapes are also possible, such asspecifically shaped apertures that correspond with particular objectsexpected to be within a particular scene or irregular apertures thatselect specific polarizations of light 102 (e.g., horizontal or verticalpolarizations).

Lens 130 may focus light 102 from the scene onto the focal plane whereaperture 120 a is positioned. With this arrangement, the light intensitycollected from the scene, at lens 130, may be focused to have a reducedcross-sectional area over which light 102 is projected (i.e., increasingthe spatial power density of light 102). For example, lens 130 mayinclude a converging lens, a biconvex lens, and/or a spherical lens,among other examples. Alternatively, lens 130 can be implemented as aconsecutive set of lenses positioned one after another (e.g., a biconvexlens that focuses light in a first direction and an additional biconvexlens that focuses light in a second direction). Other types of lensesand/or lens arrangements are also possible. In addition, system 100 mayinclude other optical elements (e.g., mirrors, etc.) positioned nearlens 130 to aid in focusing light 102 incident on lens 130 onto opaquematerial 120.

Object 198 may be any object positioned within a scene surroundingsystem 100. In implementations where system 100 is included in a LIDARdevice, object 198 may be illuminated by a LIDAR transmitter that emitslight (a portion of which may return as light 102). In exampleembodiments where the LIDAR device is used for navigation on anautonomous vehicle, object 198 may be or include pedestrians, othervehicles, obstacles (e.g., trees, debris, etc.), or road signs, amongothers.

As noted above, light 102 may be reflected or scattered by object 198,focused by lens 130, transmitted through aperture 120 a in opaquematerial 120, and measured by light detectors in array 110. Thissequence may occur (e.g., in a LIDAR device) to determine informationabout object 198. In some embodiments, light 102 measured by array 110may additionally or alternatively include light reflected or scatteredoff multiple objects, transmitted by a transmitter of another LIDARdevice, ambient light, sunlight, among other possibilities.

In some examples, the wavelength(s) of light 102 used to analyze object198 may be selected based on the types of objects expected to be withina scene and their expected distance from lens 130. For example, if anobject expected to be within the scene absorbs all incoming light of 500nm wavelength, a wavelength other than 500 nm may be selected toilluminate object 198 and to be analyzed by system 100. The wavelengthof light 102 (e.g., if transmitted by a transmitter of a LIDAR device)may be associated with a source that generates light 102 (or a portionthereof). For example, if the light is generated by a laser diode, light102 may comprise light within a wavelength range that includes 900 nm(or other infrared and/or visible wavelength). Thus, various types oflight sources are possible for generating light 102 (e.g., an opticalfiber amplifier, various types of lasers, a broadband source with afilter, etc.).

As shown, light 102 diverges as it propagates away from aperture 120 a.Due to the divergence, a detection area at array 110 (e.g., shown asshaded area illuminated by light 102) may be larger than across-sectional area of aperture 120 a. An increased detection area(e.g., measured in m²) for a given light power (e.g., measured in W) maylead to a reduced light intensity

$\left( {{e.g.},{{measured}\mspace{14mu}{in}\mspace{14mu}\frac{W}{m^{2}}}} \right)$incident on array 110.

The reduction in light intensity may be particularly beneficial inembodiments where array 110 includes SPADs or other light detectorshaving high sensitivities. For example, SPADs derive their sensitivityfrom a large reverse-bias voltage that produces avalanche breakdownwithin a semiconductor. This avalanche breakdown can be triggered by theabsorption of a single photon, for example. Once a SPAD absorbs a singlephoton and the avalanche breakdown begins, the SPAD cannot detectadditional photons until the SPAD is quenched (e.g., by restoring thereverse-bias voltage). The time until the SPAD is quenched may bereferred to as the recovery time. If additional photons are arriving attime intervals approaching the recovery time (e.g., within a factor often), the SPAD may begin to saturate, and the measurements by the SPADmay thus become less reliable. By reducing the light power incident onany individual light detector (e.g., SPAD) within array 110, the lightdetectors (e.g., SPADs) in array 110 may remain unsaturated. As aresult, the light measurements by each individual SPAD may have anincreased accuracy.

FIG. 1B is another illustration of system 100. As shown, system 100 alsoincludes a light filter 132 and a light emitter 140. Filter 132 mayinclude any optical filter configured to selectively transmit lightwithin a predefined wavelength range. For example, filter 132 can beconfigured to selectively transmit light within a visible wavelengthrange, an infrared wavelength range, or any other wavelength range ofthe light signal emitted by emitter 140. For example, optical filter 132may be configured to attenuate light of particular wavelengths or divertlight of particular wavelengths away from the array 110. For instance,optical filter 132 may attenuate or divert wavelengths of light 102 thatare outside of the wavelength range emitted by emitter 140. Therefore,optical filter 132 may, at least partially, reduce ambient light orbackground light from adversely affecting measurements by array 110.

In various embodiments, optical filter 132 may be located in variouspositions relative to array 110. As shown, optical filter 132 is locatedbetween lens 130 and opaque material 120. However, optical filter 132may alternatively be located between lens 130 and object 198, betweenopaque material 120 and array 110, combined with array 110 (e.g., array110 may have a surface screen that optical filter 132, or each of thelight detectors in array 110 may individually be covered by a separateoptical filter, etc.), combined with aperture 120 a (e.g., aperture 120a may be transparent only to a particular wavelength range, etc.), orcombined with lens 130 (e.g., surface screen disposed on lens 130,material of lens 130 transparent only to a particular wavelength range,etc.), among other possibilities.

As shown in FIG. 1B, light emitter 140 emits a light signal to bemeasured by array 110. Emitter 140 may include a laser diode, fiberlaser, a light-emitting diode, a laser bar, a nanostack diode bar, afilament, a LIDAR transmitter, or any other light source. As shown,emitter 140 may emit light which is reflected by object 198 in the sceneand ultimately measured (at least a portion thereof) by array 110. Insome embodiments, emitter 140 may be implemented as a pulsed laser (asopposed to a continuous wave laser), allowing for increased peak powerwhile maintaining an equivalent continuous power output.

FIG. 2A is a simplified block diagram of a LIDAR device 200, accordingto example embodiments. In some example embodiments, LIDAR device 200can be mounted to a vehicle and employed to map a surroundingenvironment (e.g., the scene including object 298, etc.) of the vehicle.As shown, LIDAR device 200 includes a controller, 238, a laser emitter240 that may be similar to emitter 140, and a noise limiting system 290that may be similar to system 100, a rotating platform 294, and one ormore actuators 296. System 290 includes an array 210 of light detectors,an opaque material 220 with an aperture defined therein (not shown), anda lens 230, which can be similar, respectively, to array 110, opaquematerial 120, and lens 130. It is noted that LIDAR device 200 mayalternatively include more or fewer components than those shown. Forexample, LIDAR device 200 may include an optical filter (e.g., filter132). Thus, system 290 can be implemented similarly to system 100 and/orany other noise limiting system described herein.

Device 200 may operate emitter 240 to emit light 202 toward a scene thatincludes object 298, similarly to, respectively, emitter 140, light 102,and object 198 of device 100. To that end, in some implementations,emitter 240 (and/or one or more other components of device 200) can beconfigured as a LIDAR transmitter of LIDAR device 200. Device 200 maythen detect reflections of light 202 from the scene to map or otherwisedetermine information about object 298. To that end, in someimplementations, array 210 (and/or one or more other components ofsystem 290) can be configured as a LIDAR receiver of LIDAR device 200.

Controller 238 may be configured to control one or more components ofLIDAR device 200 and to analyze signals received from the one or morecomponents. To that end, controller 238 may include one or moreprocessors (e.g., a microprocessor, etc.) that execute instructionsstored in a memory (not shown) of device 200 to operate device 200.Additionally or alternatively, controller 238 may include digital oranalog circuitry wired to perform one or more of the various functionsdescribed herein.

Rotating platform 294 may be configured to rotate about an axis toadjust a pointing direction of LIDAR 200 (e.g., direction of emittedlight 202 relative to the environment, etc.). To that end, rotatingplatform 294 can be formed from any solid material suitable forsupporting one or more components of LIDAR 200. For example, system 290(and/or emitter 240) may be supported (directly or indirectly) byrotating platform 294 such that each of these components moves relativeto the environment while remaining in a particular relative arrangementin response to rotation of rotating platform 294. In particular, themounted components could be rotated (simultaneously) about an axis sothat LIDAR 200 may adjust its pointing direction while scanning thesurrounding environment. In this manner, a pointing direction of LIDAR200 can be adjusted horizontally by actuating rotating platform 294 todifferent directions about the axis of rotation. In one example, LIDAR200 can be mounted on a vehicle, and rotating platform 294 can berotated to scan regions of the surrounding environment at variousdirections from the vehicle.

In order to rotate platform 294 in this manner, one or more actuators296 may actuate rotating platform 294. To that end, actuators 296 mayinclude motors, pneumatic actuators, hydraulic pistons, and/orpiezoelectric actuators, among other possibilities.

With this arrangement, controller 238 could operate actuator(s) 296 torotate rotating platform 294 in various ways so as to obtain informationabout the environment. In one example, rotating platform 294 could berotated in either direction about an axis. In another example, rotatingplatform 294 may carry out complete revolutions about the axis such thatLIDAR 200 scans a 360° field-of-view (FOV) of the environment. In yetanother example, rotating platform 294 can be rotated within aparticular range (e.g., by repeatedly rotating from a first angularposition about the axis to a second angular position and back to thefirst angular position, etc.) to scan a narrower FOV of the environment.Other examples are possible.

Moreover, rotating platform 294 could be rotated at various frequenciesso as to cause LIDAR 200 to scan the environment at various refreshrates. In one embodiment, LIDAR 200 may be configured to have a refreshrate of 10 Hz. For example, where LIDAR 200 is configured to scan a 360°FOV, actuator(s) 296 may rotate platform 294 for ten complete rotationsper second.

FIG. 2B illustrates a perspective view of LIDAR device 200. As shown,device 200 also includes a transmitter lens 231 that directs emittedlight from emitter 240 toward the environment of device 200.

To that end, FIG. 2B illustrates an example implementation of device 200where emitter 240 and system 290 each have separate respective opticallenses 231 and 230. However, in other embodiments, device 200 can bealternatively configured to have a single shared lens for both emitter240 and system 290. By using a shared lens to both direct the emittedlight and receive the incident light (e.g., light 202), advantages withrespect to size, cost, and/or complexity can be provided. For example,with a shared lens arrangement, device 200 can mitigate parallaxassociated with transmitting light (by emitter 240) from a differentviewpoint than a viewpoint from which light 202 is received (by system290).

As shown in FIG. 2B, light beams emitted by emitter 240 propagate fromlens 231 along a pointing direction of LIDAR 200 toward an environmentof LIDAR 200, and may then reflect off one or more objects in theenvironment as light 202. LIDAR 200 may then receive reflected light 202(e.g., through lens 230) and provide data pertaining to the one or moreobjects (e.g., distance between the one or more objects and the LIDAR200, etc.).

Further, as shown in FIG. 2B, rotating platform 294 mounts system 290and emitter 240 in the particular relative arrangement shown. By way ofexample, if rotating platform 294 rotates about axis 201, the pointingdirections of system 290 and emitter 240 may simultaneously changeaccording to the particular relative arrangement shown. Through thisprocess, LIDAR 200 can scan different regions of the surroundingenvironment according to different pointing directions of LIDAR 200about axis 201. Thus, for instance, device 200 (and/or another computingsystem) can determine a three-dimensional map of a 360° (or less) viewof the environment of device 200 by processing data associated withdifferent pointing directions of LIDAR 200 about axis 201.

In some examples, axis 201 may be substantially vertical. In theseexamples, the pointing direction of device 200 can be adjustedhorizontally by rotating system 290 (and emitter 240) about axis 201.

In some examples, system 290 (and emitter 240) can be tilted (relativeto axis 201) to adjust the vertical extents of the FOV of LIDAR 200. Byway of example, LIDAR device 200 can be mounted on top of a vehicle. Inthis example, system 290 (and emitter 240) can be tilted (e.g., towardthe vehicle) to collect more data points from regions of the environmentthat are closer to a driving surface on which the vehicle is locatedthan data points from regions of the environment that are above thevehicle. Other mounting positions, tilting configurations, and/orapplications of LIDAR device 200 are possible as well (e.g., on adifferent side of the vehicle, on a robotic device, or on any othermounting surface).

It is noted that the shapes, positions, and sizes of the variouscomponents of device 200 can vary, and are illustrated as shown in FIG.2B only for the sake of example.

Returning now to FIG. 2A, in some implementations, controller 238 mayuse timing information associated with a signal measured by array 210 todetermine a location (e.g., distance from LIDAR device 200) of object298. For example, in embodiments where emitter 240 is a pulsed laser,controller 238 can monitor timings of output light pulses and comparethose timings with timings of signal pulses measured by array 210. Forinstance, controller 238 can estimate a distance between device 200 andobject 298 based on the speed of light and the time of travel of thelight pulse (which can be calculated by comparing the timings). In oneimplementation, during the rotation of platform 294, emitter 240 mayemit light pulses (e.g., light 202), and system 290 may detectreflections of the emitted light pulses. Device 200 (or another computersystem that processes data from device 200) can then generate athree-dimensional (3D) representation of the scanned environment basedon a comparison of one or more characteristics (e.g., timing, pulselength, light intensity, etc.) of the emitted light pulses and thedetected reflections thereof.

In some implementations, controller 238 may be configured to account forparallax (e.g., due to laser emitter 240 and lens 230 not being locatedat the same location in space). By accounting for the parallax,controller 238 can improve accuracy of the comparison between the timingof the output light pulses and the timing of the signal pulses measuredby the array 210.

In some implementations, controller 238 could modulate light 202 emittedby emitter 240. For example, controller 238 could change the projection(e.g., pointing) direction of emitter 240 (e.g., by actuating amechanical stage, such as platform 294 for instance, that mounts emitter240). As another example, controller 238 could modulate the timing, thepower, or the wavelength of light 202 emitted by emitter 240. In someimplementations, controller 238 may also control other operationalaspects of device 200, such as adding or removing filters (e.g., filter132) along a path of propagation of light 202, adjusting relativepositions of various components of device 200 (e.g., array 210, opaquematerial 220 (and an aperture therein), lens 230, etc.), among otherpossibilities.

In some implementations, controller 238 could also adjust an aperture(not shown) within material 220. In some embodiments, the aperture maybe selectable from a number of apertures defined within the opaquematerial. In such embodiments, a MEMS mirror could be located betweenlens 230 and opaque material 220 and may be adjustable by controller 238to direct the focused light from lens 230 to one of the multipleapertures. In some embodiments, the various apertures may have differentshapes and sizes. In still other embodiments, the aperture may bedefined by an iris (or other type of diaphragm). The iris may beexpanded or contracted by controller 238, for example, to control thesize or shape of the aperture.

Thus, in some examples, LIDAR device 200 can modify a configuration ofsystem 290 to obtain additional or different information about object298 and/or the scene. In one example, controller 238 may select a largeraperture in response to a determination that background noise receivedby system 290 from the scene is currently relatively low (e.g., duringnight-time). The larger aperture, for instance, may allow system 290 todetect a portion of light 202 that would otherwise be focused by lens230 outside the aperture. In another example, controller 238 may selecta different aperture position to intercept the portion of light 202. Inyet another example, controller 238 could adjust the distance between anaperture and light detector array 210. By doing so, for instance, thecross-sectional area of a detection region in array 210 (i.e.,cross-sectional area of light 202 at array 210) can be adjusted as well.For example, in FIG. 1A, the detection region of array 110 is indicatedby shading on array 110.

However, in some scenarios, the extent to which the configuration ofsystem 290 can be modified may depend on various factors such as a sizeof LIDAR device 200 or system 290, among other factors. For example,referring back to FIG. 1A, a size of array 110 may depend on an extentof divergence of light 102 from a location of aperture 120 a to alocation of array 110. Thus, for instance, the maximum vertical andhorizontal extents of array 110 may depend on the physical spaceavailable for accommodating system 100 within a LIDAR device. Similarly,for instance, an available range of values for the distance betweenarray 110 and aperture 120 a may also be limited by physical limitationsof a LIDAR device where system 100 is employed. Accordingly, exampleimplementations are described herein for space-efficient noise limitingsystems that increase a detection area in which light detectors canintercept light from the scene and reduce background noise.

In some scenarios, where emitter 240 and lens 230 have differentphysical locations, the scanned representation of object 298 may besusceptible to parallax associated with a spatial offset between thetransmit path of light 202 emitted by emitter 240 and the receive pathof reflected light 202 incident on lens 230. Accordingly, exampleimplementations are described herein for reducing and/or mitigating theeffects of such parallax. In one example, device 200 may alternativelyinclude emitter 240 within system 290 such that the LIDAR transmit andreceive paths of LIDAR 200 are co-aligned (e.g., both paths propagatethrough lens 230).

It is noted that the various functional blocks shown for the componentsof device 200 can be redistributed, rearranged, combined, and/orseparated in various ways different than the arrangement shown.

FIG. 3A is an illustration of a system 300 that includes a waveguide360, according to example embodiments. In some implementations, system300 can be used with device 200 instead of or in addition to transmitter240 and system 290. As shown, system 300 may measure light 302 reflectedby an object 398 within a scene similarly to, respectively, system 100,light 102, and object 198. Further, as shown, system 300 includes alight detector array 310, an opaque material 320, an aperture 320 a, alens 330, and a light source 340, which may be similar, respectively, toarray 110, material 120, aperture 120 a, lens 130, and emitter 140. Forthe sake of example, aperture 320 a is shown to have a different shape(elliptical) than a shape of aperture 120 a (rectangular). Otheraperture shapes are possible.

As shown, system 300 also includes waveguide 360 (e.g., opticalwaveguide, etc.) arranged along a propagation path of focused light 302(transmitted through aperture 320 a). For example, as shown, a firstportion of focused light 302 is projected onto waveguide 360 (e.g.,shaded region) and a second portion of focused light 302 is projectedonto array 310.

FIG. 3B illustrates a cross-section view of system 300. As best shown inFIG. 3B, at least a portion of focused light 302 may propagate from lens330 to array 310 without propagating through waveguide 360. As shown inFIGS. 3A and 3B, waveguide 360 is arranged to receive emitted light 304emitted by light source 340 and projected onto side 360 a of waveguide360.

To that end, waveguide 360 can be formed from a glass substrate (e.g.,glass plate, etc.), a photoresist material (e.g., SU-8, etc.), or anyother material at least partially transparent to one or more wavelengthsof light 304. Further, in some examples, waveguide 360 may be formedfrom a material that has a different index of refraction than materialssurrounding waveguide 360. Thus, waveguide 360 may guide at least aportion of light propagating therein via internal reflection (e.g.,total internal reflection, frustrated total internal reflection, etc.)at one or more edges, sides, walls, etc., of waveguide 360. For example,waveguide 360 may guide emitted light 304 incident on side 360 a towardside 360 b (opposite to side 360 a) via internal reflection at sides 360c, 360 d, and/or other sides along a length of waveguide 360.

Further, as shown in FIGS. 3A and 3B, system 300 also includes a mirror350. Mirror 350 may include any reflective material that hasreflectivity characteristics suitable for reflecting (at leastpartially) wavelengths of light 304. To that end, a non-exhaustive listof example reflective materials includes gold, aluminum, other metal ormetal oxide, synthetic polymers, hybrid pigments (e.g., fibrous claysand dyes, etc.), among other examples.

Mirror 350 may be tilted (e.g., as compared to an orientation of side360 a) at an offset angle 390 toward side 360 c of waveguide 360. Forexample, an angle 392 between side 360 a and side 360 c may be greaterthan angle 390 between mirror 350 and side 360 c. In one embodiment,offset or tilting angle 390 of mirror 350 is 45°, and angle 392 betweenside 360 a and side 360 c is 90°. However, other angles are possible. Ingeneral, mirror 350 is positioned along a path of at least a portion ofguided light 304 propagating inside waveguide 360 (received at side 360a and guided toward side 360 b). In the embodiment shown, mirror 350 isdisposed on side 360 b of waveguide 360. For instance, waveguide 360 canbe formed such that angle 390 between side 360 c and side 360 b isdifferent than angle 392 between side 360 c and side 360 a. Mirror 350can then be disposed on side 360 b (e.g., via chemical vapor deposition,sputtering, mechanical coupling, or another process). However, in otherembodiments, mirror 350 can be alternatively disposed inside waveguide360 (e.g., between sides 360 a and 360 b).

As noted above, waveguide 360 may guide at least a portion of emittedlight 304, via total internal reflection for instance, inside waveguide360 toward side 360 b. For example, as best shown in FIG. 3B, waveguide360 may extend vertically (e.g., lengthwise) between sides 360 a and 360b. In some examples, side 360 c may correspond to an interface between arelatively high index of refraction medium (e.g., photoresist, epoxy,etc.) of waveguide 360 and a relatively lower index of refraction medium(e.g., air, vacuum, optical adhesive, glass, etc.) adjacent to side 360c. Thus, for instance, if guided light 304 propagates to side 360 c atless than the critical angle (e.g., which may be based on a ratio ofindexes of refractions of the adjacent materials at side 360 c, etc.),then the guided light incident on side 360 c (or a portion thereof) maybe reflected back into waveguide 360. Similarly, guided light incidenton side 360 d at less than the critical angle may also be reflected backinto waveguide 360. Thus, waveguide 360 may control divergence of guidedlight via internal reflection at sides 360 c and 360 d, for example.Similarly, waveguide 360 may extend through the page in the illustrationof FIG. 3B between two opposite sides of waveguide 360 to controldivergence of guided light 304.

Thus, at least a portion of emitted light 304 (received at side 360 a)may reach tilted side 360 b. Mirror 350 (e.g., disposed on side 360 b)may then reflect the at least portion of guided light 304 toward side360 c and out of waveguide 360. For example, offset or tilting angle 390can be selected such that reflected light 304 from mirror 350 propagatestoward a particular region of side 360 c at greater than the criticalangle. As a result, reflected light 304 may be (at least partially)transmitted through side 360 c rather than reflected (e.g., via totalinternal reflection etc.) back into waveguide 360. Further, in theembodiment shown, aperture 320 a could be located adjacent to theparticular region of side 360 c, and may thus transmit light 304 towardlens 330. Lens 330 may then direct light 304 toward a scene.

Emitted light 304 may then reflect off one or more objects (e.g., object398) in the scene, and return to lens 330 (e.g., as part of light 302from the scene). Lens 330 may then focus light 302 (including thereflections of the emitted light beams) through aperture 320 a.

As best shown in FIG. 3A, a first portion of focused light 302 may befocused onto waveguide 360 (e.g., shaded region). In some instances, thefirst portion of focused light 302 may propagate through transparentregions of waveguide 360 (e.g., from side 360 c to side 360 d and thenout of waveguide 360 toward array 310, without being intercepted bymirror 350. However, in some examples, the first portion of focusedlight 302 may be at least partially intercepted by mirror 350 and thenreflected away from array 310 (e.g., guided inside waveguide 360, etc.).To mitigate this, in some implementations, mirror 350 can be configuredto have a small size relative to aperture 320 a and/or a projection areaof focused light 302 at the location of mirror 350. In these examples, alarger portion of focused light 302 may propagate adjacent to mirror 350(and/or waveguide 360) to continue propagating toward array 310.Alternatively, mirror 350 can be formed from a partially or selectivelyreflective material (e.g., half mirror, dichroic mirror, etc.) thattransmits at least a portion of focused light 302 incident thereonthrough mirror 350 for propagation toward array 310.

As noted above, system 300 can be used with LIDAR device 200, inaddition to or instead of transmitter 240 and system 290. In suchimplementations, system 300 may emit light 304 from a same location(e.g., aperture 320 a) as the location at which system 300 receivesfocused light 302 (e.g., aperture 320 a). Because the transmit path ofemitted light 304 and the receive path of focused light 302 areco-aligned (e.g., both paths are from the point-of-view of aperture 320a, system 300 may be less susceptible to the effects of parallax. Inturn, a LIDAR device that employs system 300 could generate arepresentation of the scanned scene (e.g., data point cloud, etc.) thatis less susceptible to errors related to parallax.

It is noted that the sizes, positions, orientations, and shapes of thecomponents and features of system 300 shown are not necessarily toscale, but are illustrated as shown only for convenience in description.It is also noted that system 300 may include fewer or more componentsthan those shown, and one or more of the components shown could bearranged differently, physically combined, and/or physically dividedinto separate components.

In a first embodiment, the relative arrangement of array 310, aperture320 a, and waveguide 360 can vary. In a first example, opaque material320 (and thus aperture 320 a) can be alternatively disposed betweenarray 310 and waveguide 360. For instance, waveguide 360 can bepositioned adjacent to an opposite side of opaque material 320, whilestill transmitting emitted light 304 along a path that overlaps thepropagation path of focused light 302 transmitted through aperture 320a. In a second example, array 310 can be alternatively disposed betweenwaveguide 360 and opaque material 320. For instance, array 310 mayinclude an aperture (e.g., cavity, etc.) through which emitted light 304propagates toward aperture 320 a (and lens 330).

In a second embodiment, array 310 can be replaced by a single lightdetector rather than a plurality of light detectors.

In a third embodiment, a distance between waveguide 360 and aperture 320a can vary. In one example, waveguide 360 can be disposed along (e.g.,in contact with, etc.) opaque material 320. For instance, side 360 c maybe substantially coplanar with or proximal to aperture 320 a. However,in other examples (as shown), waveguide 360 can be positioned at adistance (e.g., gap, etc.) from opaque material 320 (and aperture 320a).

In a fourth embodiment, system 300 could optionally include an actuatorthat moves lens 330, opaque material 320, and/or waveguide 360 toachieve a particular optical configuration (e.g., focus configuration,etc.) while scanning the scene. More generally, optical characteristicsof system 300 can be adjusted according to various applications ofsystem 300.

In a fifth embodiment, the position and/or orientation of aperture 320 acan vary. In one example, aperture 320 a can be disposed along the focalplane of lens 330. In another example, aperture 320 a can be disposedparallel to the focal plane of lens 330 but at a different distance tolens 330 than the distance between the focal plane and lens 330. In yetanother example, aperture 320 a can be arranged at an offset orientationrelative to the focal plane of lens 330. For instance, system 300 canrotate (e.g., via an actuator) opaque material 320 (and/or waveguide360) to adjust the entry angle of light 302 and/or 304 into aperture 320a. By doing so, for instance, a controller (e.g., controller 238) canfurther control optical characteristics of system 300 depending onvarious factors such as lens characteristics of lens 330, environment ofsystem 300 (e.g., to reduce noise/interference arriving from aparticular region of the scanned scene, etc.), among other factors.

In a sixth embodiment, waveguide 360 can alternatively have acylindrical shape or any other shape. Additionally, in some examples,waveguide 360 can be implemented as a rigid structure (e.g., slabwaveguide) or as a flexible structure (e.g., optical fiber).

FIG. 4A illustrates a first cross-section view of a system 400 thatincludes multiple waveguides 460, 462, 464, 466, according to exampleembodiments. For purposes of illustration, FIG. 4A shows an x-y-z axis,in which the z-axis extends through the page. System 400 may be similarto systems 100, 290, and/or 300, and can be used with device 200 insteadof or in addition to system 290 and transmitter 240. For example, theside of waveguide 460 along the surface of the page may be similar toside 360 c of waveguide 360.

As shown, system 400 includes an optical element 434; a transmitter 440that includes one or more light sources similar to light source 340; aplurality of mirrors 450, 452, 454, 456, each of which may be similar tomirror 350; and a plurality of waveguides 460, 462, 464, 466, each ofwhich may be similar to waveguide 360.

Optical element 434 may be interposed between transmitter 440 andwaveguides 460, 462, 464, 466, and may be configured to redirect, focus,collimate, and/or otherwise adjust optical characteristics of emittedlight 404. To that end, optical element 434 may comprise any combinationof optical elements, such as lenses, mirrors, cylindrical lenses, lightfilters, etc.

In one example, optical element 434 may comprise a cylindrical lens,and/or other optical element configured to (at least partially)collimate and/or direct light beams 404 (e.g., emitted by transmitter440) as light portions 404 a, 404 b, 404 c, 404 d toward waveguides 460,462, 464, 466. In this example, optical element 434 may transmit arelatively larger amount of energy from emitted light portion 404 a intowaveguide 460 by collimating the light beams. Alternatively oradditionally, in this example, optical element 434 may direct emittedlight portion 404 a into waveguide 460 at a particular angle of entry(e.g., less than the critical angle of waveguide 460, etc.) that issuitable for light beam(s) 404 a to be guided inside waveguide 460(e.g., via total internal reflection, etc.).

In the embodiment shown, optical element 434 can be implemented as asingle optical element interposed between transmitter 440 and waveguides460, 462, 464, 466. For example, optical element 434 can be implementedas an optical fiber that is arranged as a cylindrical lens to at leastpartially collimate light beams 404 a, 404 b, 404 c, 404 d. In otherembodiments, optical element 434 can be alternatively implemented asmultiple physically separate optical elements (e.g., multiplecylindrical lenses), among other possibilities.

Transmitter 440 may be configured to emit light 404 similarly to,respectively, light source 340 and emitted light 304. To that end,transmitter 440 may include one or more light sources (e.g., laser bars,LEDs, diode lasers, etc.).

In a first embodiment, transmitter 440 may comprise a single lightsource that transmits light 404. For example, each of light portions 404a, 404 b, 404 c, 404 d may originate from a single light source. Withthis arrangement, for example, a single light source can be used todrive four different transmit channels of system 400.

In a second embodiment, a given light source in transmitter 440 can beused to drive fewer or more than four transmit channels. For example,transmitter 440 may include a first light source that provides lightportions 404 a, 404 b, and a second light source that provides lightportions 404 c, 404 d. In one implementation, a single light source canbe used to drive eight transmit channels.

In a third embodiment, transmitter 440 may include a separate lightsource for driving each transmit channel. For example, a first lightsource may emit light portion 404 a, a second light source may emitlight portion 404 b, a third light source may provide light portion 404c, and a fourth light source may emit light portion 404 d.

Regardless of the number of light sources in transmitter 440, emittedlight beams 404 a, 404 b, 404 c, 404 d may then propagate along separatetransmit paths toward an environment of system 400. By way of example,light beam(s) 404 a could be transmitted through a first side ofwaveguide 460 (e.g., similar to side 360 a of waveguide 360). Waveguide460 may then guide light 404 a in a lengthwise direction of waveguide460 toward a second opposite side (e.g., similar to side 360 b) ofwaveguide 460, where mirror 450 is located. Mirror 450 may then reflectguided light 404 a out of the page (along z-axis), and toward a scene.Thus, light portion 404 a may define a first transmit channel (e.g.,LIDAR transmit channel, etc.) that is associated with the transmit pathdescribed above.

Similarly, light beam(s) 404 b could define a second transmit channelassociated with a transmit path defined by waveguide 462 and mirror 452;light beam(s) 404 c could define a third transmit channel associatedwith a transmit path defined by waveguide 464 and mirror 454; and lightbeam(s) 404 d could define a fourth transmit channel associated with atransmit path of light defined by waveguide 466 and mirror 456. Withthis arrangement, system 400 may emit a pattern of light beams toward ascene.

FIG. 4B illustrates a second cross-section view of system 400, where thez-axis is also pointing out of the page. As shown in FIG. 4B, system 400also includes an opaque material 420, which may be similar to opaquematerial 320 of system 300. Opaque material 420 may define a pluralityof apertures, exemplified by apertures 420 a, 420 b, 420 c, and 420 d,each of which may be similar to aperture 320 a. For example, aperture420 a may be aligned (e.g., adjacent, overlapping, etc.) with an outputend of waveguide 460 (e.g., where light 404 a exits waveguide 460). Forexample, aperture 420 a may overlap mirror 450 in the direction of thez-axis. Similarly, aperture 420 b can be aligned with an output end ofwaveguide 462, aperture 420 c could be aligned with an output end ofwaveguide 464, and aperture 420 d could be aligned with an output end ofwaveguide 466. Thus, each of apertures 420 a, 420 b, 420 c, 420 d may beco-aligned with respective transmit paths of emitted light portions 404a, 404 b, 404 c, 404 d, and may thus define positions of the fourtransmit channels of system 400.

Additionally, in some examples, focused light from the scene (e.g.,propagating into the page in FIG. 4B) may be projected onto opaquematerial 420 similarly to focused light 302 incident on opaque material320. To that end, system 400 may provide multiple receive channelsassociated with respective portions of the focused light projected onopaque material 420 at the respective positions of apertures 420 a, 420b, 420 c, 420 d.

For example, a first portion of the focused light transmitted throughaperture 420 a could be intercepted by a first light detector associatedwith a first receive channel, a second portion of the focused lighttransmitted through aperture 420 b could be intercepted by a secondlight detector associated with a second receive channel, a third portionof the focused light transmitted through aperture 420 c could beintercepted by a third light detector associated with a third receivechannel, and a fourth portion of the focused light transmitted throughaperture 420 d could be intercepted by a fourth light detectorassociated with a fourth receive channel.

With this arrangement, system 400 can obtain a one-dimensional (1D)image (e.g., horizontal arrangement of pixels or LIDAR data points,etc.) of the scene. For instance, a first pixel or data point in the 1Dimage could be based on data from the first receive channel associatedwith aperture 420 a, and a second pixel in the 1D image could be basedon data from the second receive channel associated with aperture 420 b.Additionally, with this arrangement, each transmit channel may beassociated with a transmit path that is co-aligned (through a respectiveaperture) with a receive path associated with a corresponding receivechannel. Thus, system 400 can mitigate the effects of parallax byproviding pairs of co-aligned transmit/receive channels defined by thelocations of apertures 420 a, 420 b, 420 c, 420 d.

Although waveguides 460, 462, 464, 466 are shown in FIG. 4A to be in ahorizontal (e.g., along x-y plane) arrangement, in some examples, system400 may include waveguides in a different arrangement. In a firstexample, the waveguides can alternatively or additionally be arrangedvertically (e.g., along y-z plane) to obtain a vertical 1D image (orline of LIDAR data points) representation of the scene. In a secondexample, the waveguides can alternatively be arranged both horizontallyand vertically (e.g., as a two-dimensional grid) to obtain atwo-dimensional (2D) image (or 2D grid of LIDAR data points) of thescene.

FIG. 4C illustrates a third cross section view of system 400, in whichthe z-axis is also pointing out of the page. For example, one or more ofthe components of system 400 shown in FIG. 4B may be positioned above orbelow (e.g., along z-axis) one or more of the components shown in FIG.4A.

As shown, system 400 also includes a support structure 470 that mounts aplurality of receivers, exemplified by 410, 412, 414, 418. Further, asshown, system 400 also includes one or more light shields 472.

Each of receivers 410, 412, 414, and 416 may include one or more lightdetectors similar to the light detectors in any of arrays 110, 210,and/or 310. Receivers 410, 412, 414, 416 may be arranged to interceptfocused light that is transmitted, respectively, through apertures 420a, 420 b, 420 c, 420 d (shown in FIG. 4B). In one embodiment, receivers410, 412, 414, 416 may be positioned to overlap (e.g., in the directionof the z-axis), respectively, mirrors 450, 452, 454, 456 (i.e., theoutput ends of waveguides 460, 462, 464, 463). In some examples, each ofreceivers 410, 412, 414, 416 may include a respective array of lightdetectors connected in parallel to one another (e.g., SiPM, MPCC, etc.).In other examples, each receiver may include a single light detector.

Support structure 470 may include a printed circuit board (PCB) to whichthe light detectors of receivers 410, 412, 414, 416 are mounted. By wayof example, a first group of light detector(s) may define a firstreceive channel associated with receiver 410; a second adjacent groupmay define a second receive channel associated with receiver 412; athird adjacent group may define a third receive channel associated withreceiver 414; and a fourth group may define a fourth receive channelassociated with receiver 416. Alternatively or additionally, structure470 may include a different type of solid material that has materialcharacteristics suitable for supporting receivers 410, 412, 414, 416.

Light shield(s) 472 may comprise one or more light absorbing materials(e.g., black carbon, black chrome, black plastic, etc.) arranged aroundreceivers 410, 412, 414, 416. To that end, for example, light shield(s)472 may prevent (or reduce) light from external sources (e.g., ambientlight, etc.) from reaching receivers 410, 412, 414, 416. Alternativelyor additionally, for example, light shield(s) 472 can prevent or reducecross-talk between receive channels associated with receivers 410, 412,414, 416. Thus, in this example, light shield(s) 472 may be configuredto optically separate receivers 410, 412, 414, 416, etc., of system 400from one another. As shown, for instance, light shield(s) 472 may beshaped in a honeycomb structure configuration, where each cell of thehoneycomb structure shields light detectors of a first receiver (e.g.,receiver 410) from light propagating toward light detectors in a secondadjacent receiver (e.g., receiver 412). With this arrangement, system400 may provide for space-efficient placement of multiple arrays oflight detectors (e.g., along a surface of structure 470) that are eachaligned with a respective waveguide in system 400. Other shapes and/orarrangements of light shield(s) 472 (e.g., rectangular-shaped cells,other shapes of cells, etc.) are possible.

FIG. 4D illustrates a fourth cross-section view of system 400, where they-axis is pointing through of the page. As shown, waveguide 460 includessides 460 a and 460 b which may be similar, respectively, to sides 360 aand 360 b of waveguide 360. Further, as shown, system 400 also includesa lens 430, a light filter 432, a plurality of substrates 474, 476, amaterial 478 disposed between substrates 474 and 476, a supportstructure 480, and a plurality of adhesives 482, 484.

Lens 430 may be similar to lens 330. For example, lens 430 may focuslight from a scene toward opaque material 420. Respective portions offocused light 402 may then be transmitted, respectively, throughapertures 420 a, 420 b, 420 c, 420 d (shown in FIG. 4B). In FIG. 4D forexample, a portion 402 a of focused light 402 may be transmitted throughaperture 420 a onto waveguide 460 and receiver 410. As shown in FIG. 4D,waveguide 460 may be at a first distance to lens 430, and receiver 410may be at a second (greater) distance to lens 430. Further, as shown inFIG. 4D, emitted light portion 404 a may be reflected by mirror 450through aperture 420 a and toward lens 430.

Light filter 432 may be similar to light filter 132. For example, lightfilter 432 may include one or more devices configured to attenuatewavelengths of light 402 (e.g., other than wavelengths of emitted light404, etc.). In some examples, substrate 476 (and filter 434) may extendhorizontally (through the page; along the y-axis) to similarly attenuatelight propagating toward waveguides 462, 464, and 466 (shown in FIG.4A). As shown in FIG. 4D, filter 432 may be disposed on a given side ofsubstrate 476 (e.g., between substrate 476 and receiver 410).

In another embodiment, filter 432 may be alternatively disposed on theopposite side of substrate 476 (between substrates 474, 476), or at anyother location in system 400 along a propagation path of light 402(i.e., prior to detection of light 402 a at receiver 410). In yetanother embodiment, substrate 476 can be formed from a material that haslight filtering characteristics of filter 432. Thus, in this embodiment,filter 432 can be omitted from system 400 (i.e., the functions of filter432 can be performed by substrate 476). In still another embodiment,filter 432 can be implemented as multiple (e.g., smaller) filters thatare each disposed between substrate 476 and a respective one of thereceivers. For instance, a first filter can be used to attenuate lightpropagating toward receiver 410, and a second separate filter can beused to attenuate light propagating toward receiver 412, etc. Referringback to FIG. 4C by way of example, each filter can be disposed in (oradjacent to) each of cells 410, 412, 414, 416, etc. of the honeycombstructure of light shield 472.

Substrates 474 and 476 can be formed from any transparent materialconfigured to transmit at least some wavelengths of light (e.g.,wavelengths of light 404, etc.) through the respective substrates. Inone embodiment, substrates 474 and 476 may include glass wafers.

Material 478 may be formed from any optical material that has opticalcharacteristics suitable for defining an optical medium around waveguide460. For example, material 478 may include a gas, liquid, or solidmaterial having a lower index of refraction than an index of refractionof waveguide 460 (and waveguides 462, 464, 466). In some examples,material 478 may comprise an optical adhesive that couples substrates474 and 476 to one another. In these examples, material 478 may beconfigured to support waveguide 460 in a particular position relative tolens 430 (and/or aperture 420 a).

As noted above, in some examples, material 478 may comprise an adhesivematerial that mechanically attaches two or more components of system 400to one another. In one example, material 478 (configured as an opticaladhesive) can be disposed between two particular components in a liquidform, and may then cure to a solid form to attach the two particularcomponents to one another. To that end, example optical adhesives mayinclude photopolymers or other polymers that can transform from a clear,colorless, liquid form into a solid form (e.g., in response to exposureto ultraviolet light or other energy source).

As shown, material 478 may be disposed between and in contact withsubstrates 476 and 478. Additionally, as shown, material 478 is incontact with one or more sides of waveguide 460. As noted above,material 478 may have a lower index of refraction than the material ofwaveguide 460. The difference between the indexes of refraction atwalls, sides, etc., of waveguide 460 adjacent to material 478 may causeguided light inside waveguide 460 to internally reflect back intowaveguide 460 at the interface(s) between waveguide 460 and material478. In one implementation, the waveguides of system 400 can be disposedon substrate 474, then material 478 can be disposed on substrate 474 andon the waveguides to support and/or maintain the waveguides in aparticular relative arrangement, and then substrate 476 can then bedisposed on material 478 to attach substrate 474 with substrate 476.

Support structure 480 may be formed from similar materials as structure470 (e.g., PCB, solid platform, etc.). As shown, structure 480 can beconfigured as a platform that mounts transmitter 440. For example,structure 480 can be implemented as a PCB on which one or more lightsources (e.g., laser bar, etc.) of transmitter 440 are mounted. To thatend, structure 480 could optionally include wiring or other circuitryfor transmitting power and signals to operate transmitter 440. In someexamples, structure 470 may similarly include wiring and/or circuitryfor transmitting power and/or communicating signals with receiver 410 tooperate receiver 410.

Adhesives 482, 484 can be formed from any adhesive material suitable forattaching or otherwise coupling at least two components of system 400 toone another. A non-exhaustive list of example adhesive materialsincludes non-reactive adhesives, reactive adhesives, solvent-basedadhesives (e.g., dissolved polymers, etc.), polymer dispersion adhesives(e.g., polyvinyl acetate, etc.), pressure-sensitive adhesives, contactadhesives (e.g., rubber, polycholoroprene, elastomers, etc.), hotadhesives (e.g., thermoplastics, ethylene-vinyl acetates, etc.),multi-component adhesives (e.g., thermosetting polymers, polyesterresin—polyurethane resin, polypols—polyurethane resin, acrylicpolymers—polyurethane resins, etc.), one-part adhesives, ultraviolet(UV) light curing adhesives, light curing materials (LCM), heat curingadhesives (e.g., thermoset epoxies, urethanes, polymides, etc.), andmoisture curing adhesives (e.g., cyanoacrylates, urethanes, etc.), amongothers.

In some examples, adhesives 482, 484 may comprise optical adhesivematerials (e.g., materials that are transparent to at least somewavelengths of light 404), similarly to material 478. In other examples,adhesives 482, 484 may comprise adhesive materials that are opaqueand/or otherwise attenuate or prevent at least some wavelengths oflight.

The assembly of components between (and including) substrates 474 and476 may together provide a “chip” assembly of the waveguides. Forinstance, substrate 474 may define a top side of the chip assembly ofsystem 400, and substrate 476, adhesive 482, and structure 480 maytogether define a bottom side of the chip assembly.

Additionally, in the example shown, optical element 434 may be disposedon a same surface of substrate 474 on which waveguide 460 is mounted.However, in other examples, optical element 434 could be disposed on adifferent surface inside the chip assembly. In a first example, opticalelement 434 could be mounted on structure 480. In a second example,optical element 434 could be mounted on and/or attached to side 460 a ofwaveguide 460. In a third example, although not shown, substrate 476could alternatively extend further horizontally (e.g., along x-axis) tooverlap the location of optical element 434 (e.g., structure 480 couldbe narrower horizontally, etc.). In this example, optical element 434could be disposed on substrate 476. In a fourth example, optical element434 could alternatively be disposed on another support structure (notshown) inside the chip assembly. Other examples are possible.

Additionally, transmitter 440 could also be included inside the chipassembly. For example, as shown, adhesive 482 may couple (e.g., attach)transmitter 440 and/or structure 480 to substrate 476. Further, forexample, adhesive 484 may couple or attach structure 480 (and/ortransmitter 440) to substrate 474.

By disposing transmitter 440 and optical element 434 inside the chipassembly, system 400 could shield and/or prevent damage to these opticalcomponents. Additionally, for instance, the chip assembly of system 400could support and/or maintain these optical components in a particularrelative arrangement with respect to one another. By doing so, forinstance, system 400 may be less susceptible to calibration and/ormisalignment errors that would occur if the particular relativearrangement of these components is inadvertently changed (e.g., if oneof these components is moved differently than the other components).

As best shown in FIG. 4A, in some examples, waveguides 462, 464, 466 canbe disposed on substrate 474 similarly to waveguide 460 (e.g., arrangedhorizontally in the x-y plane). Further, in some examples, system 400may include additional (or fewer) waveguides in the same horizontalplane (e.g., disposed on substrate 474, etc.). Further, referring backto FIG. 4C, these additional waveguides can similarly be alignedrespective cells of the honeycomb-shaped light shield structure 472.

In some examples, system 400 may include waveguides mounted along adifferent horizontal plane than the plane in which waveguides 460, 462,464, 466 are located. The waveguides in the different horizontal planecould be aligned with additional receivers of system 400. The additionalreceivers, for instance, may be disposed within respective cells of thehoneycomb-shaped light shield(s) 472 shown in FIG. 4C. Further, opaquematerial 420 may include additional apertures aligned with theseadditional waveguides. With this arrangement, system 400 can imageadditional regions of the focal plane of lens 430 to provide atwo-dimensional (2D) scanned image (or 2D grid of LIDAR data points).Alternatively or additionally, the entire assembly of system 400 can berotated or moved to generate the 2D scanned image of the scene.

In one example, opaque material 420 may define a grid of apertures alongthe focal plane of lens 430, and each aperture in the grid may transmitlight for a receive channel associated with a respective portion of theFOV of lens 430. In one embodiment, opaque material 420 may comprisefour rows of 64 apertures, where each row of horizontally (e.g., alongy-axis) adjacent apertures is separated by a vertical offset (e.g.,along z-axis) from another row of apertures. In this embodiment, system400 could thus provide 4*64=256 receive channels, and 256 co-alignedtransmit channels. In other embodiments, system 400 may include adifferent number of transmit/receive channels (and thus a differentnumber of associated apertures).

In some implementations, system 400 can be rotated about an axis whilescanning a surrounding environment using the multiple transmit andreceive channels. Referring back to FIG. 2 for example, system 400 canbe mounted on a rotating platform, similar to platform 294, that rotatesabout an axis (e.g., using actuator 296, etc.) while system 400 istransmitting light pulses and detecting reflections thereof (viaapertures 420 a, 420 b, 420 c, 420 d, etc.). In this example, acontroller (e.g., controller 238) or other computer system can receiveLIDAR data collected using the co-aligned transmit/receive channels ofsystem 400, and then process the LIDAR data to generate a 3Drepresentation of the environment of system 400. In one implementation,system 400 can be employed in a vehicle, and the 3D representation maybe used to facilitate various operations of the vehicle (e.g., detectand/or identify objects around the vehicle, facilitate autonomousnavigation of the vehicle in the environment, display the 3Drepresentation to a user of the vehicle via a display, etc.).

It is noted that the various sizes, shapes, and positions (e.g.,distance between adjacent waveguides, etc.) shown in FIGS. 4A-4D for thevarious components of system 400 are not necessarily to scale but areillustrated as shown only for convenience in description.

FIG. 5 illustrates a cross-section view of another system 500, accordingto example embodiments. System 500 may be similar to systems 100, 290,300, and/or system 400, for example. For convenience in description,FIG. 5 shows an x-y-z axis, where the y-axis is pointing out of thepage. To that end, the cross-section view of system 500 shown in FIG. 5may be similar to the cross-section view of system 400 shown in FIG. 4C.

As shown in FIG. 5, system 500 includes a receiver 510, an opaquematerial 520, an aperture 520 a, a light filter 532, an optical element534, a transmitter 540, a mirror 550, a waveguide 560 having sides 560 aand 560 b, a support structure 570, one or more light shields 572,substrates 574, 576, material 578, support structure 580, and adhesives582, 584, which may be similar, respectively, to receiver 410, opaquematerial 420, aperture 420 a, light filter 432, optical element 434,transmitter 440, mirror 450, waveguide 460, sides 460 a and 460 b,support structure 470, light shield(s) 472, substrates 474, 476,material 578, support structure 480, and adhesives 482, 484 of system400. To that end, focused light 502, focused light portion 502 a,emitted light 504, and emitted light portion 504 a, may be similar,respectively, to focused light 402, focused light portion 402 a, emittedlight 404, and emitted light portion 404 a.

As noted above, example systems herein may employ various arrangementsof a lens, waveguide, and light detector(s) to define co-alignedtransmit/receive paths.

In a first example arrangement, system 400 (as best shown in FIG. 4D)includes aperture 420 a interposed between waveguide 460 and lens 430.In this example, both emitted light 404 a and focused light 402 a aretransmitted through the same aperture 420 a, and may thus be associatedwith co-aligned transmit/receive paths.

In a second example arrangement, system 500 (as shown in FIG. 5)includes aperture 520 a interposed between waveguide 560 and receiver510. Thus, in system 500, focused light 502 a is transmitted throughaperture 520 a, but emitted light 504 a is not transmitted throughaperture 520 a. However, in system 500, an output end of waveguide 560(e.g., where mirror 550 is located) may be interposed between aperture520 a and lens 530 (e.g., along the propagation path of focused light502 a) to direct emitted light 504 a from a same or similarpoint-of-view as focused light 502 a that is transmitted throughaperture 520 a. Thus, the transmit path of emitted light 504 a and thereceive path of focused light 502 a may also be co-aligned (even thoughemitted light 504 a and focused light 502 a are not transmitted throughthe same aperture).

In a third example arrangement, receiver 510 could alternatively bedisposed between waveguide 560 and opaque material 520. For instance,receiver 510 may include a cavity through which emitted light 504 a canpropagate toward aperture 520 a.

In a fourth example arrangement, receiver 510 and a waveguide 560 couldalternatively be positioned at a same distance to lens 530. Referringback to FIG. 3A for instance, one or more light detectors of array 310(e.g., one or more columns, rows, or other group of light detectors)could be replaced with waveguide 360 such that mirror 350 directsemitted light 304 toward the same aperture 320 a used for transmittingfocused light 302 toward array 310.

In a fifth example arrangement, substrate 576 can be alternativelyomitted from system 500, and opaque material 520 (e.g., pinhole array)can be instead disposed on filter 532 or on light shield(s) 572.Referring back to FIG. 4B for example, the aperture array defined byopaque material 420 can be alternatively disposed onto the honeycombbaffle structure of light shield(s) 472 shown in FIG. 4C.

Other example arrangements are possible. Thus, in various examples,system 500 may include more, fewer, or different components than thoseshown. Further, the arrangement of the various components may varywithout departing from the scope of the present disclosure.

It is noted that some of the components of system 500 are omitted fromthe illustration of FIG. 5 for convenience in description. For example,although not shown, system 500 may also include multiple waveguides,and/or one or more other components such as any of the components ofsystems 100, 290, 300, 400, and/or device 200. For instance, system 500may include multiple waveguides disposed on substrate 574 in ahorizontal arrangement (along x-y plane), similarly to waveguides 460,462, 464, 466 of system 400.

FIG. 6 illustrates another system 600, according to example embodiments.System 600 may be similar to systems 100, 290, 300, 400, and/or 500, andcould be used with LIDAR device 200 instead of or in addition totransmitter 240 and system 290. For convenience in description, FIG. 6shows an x-y-z axis, where the z-axis is pointing through the page. Tothat end, the cross-section view of system 600 shown in FIG. 6 may besimilar to the cross-section view of system 400 shown in FIG. 4A.

As shown, system 600 includes a transmitter 640, an optical element 634,a plurality of mirrors 650, 652, 654, 656, and a waveguide 660, whichmay be similar, respectively, to transmitter 440, optical element 434,mirrors 450, 452, 454, 456, and waveguide 460 of system 400. Further, asshown, system 600 also includes reflectors 690 and 692.

Transmitter 640 may emit light 604 into waveguide 660 via opticalelement 634, similarly to, respectively, transmitter 440, light 404,waveguide 460, and optical element 434.

As shown in FIG. 6 however, waveguide 660 includes multiple output ends660 b, 660 c, 660 d, and 660 e. Thus, for example, system 600 maypresent an alternative embodiment for providing multipletransmit/receive channels by using a single waveguide 660 instead ofusing multiple waveguides 460, 462, 464, 466.

For example, each of output ends 660 b, 660 c, 660 d, 660 e may besimilar to side 460 b of waveguide 460. Output end 660 b may include atilted mirror 650 (disposed thereon) that reflects a first portion ofemitted light 604 out of the page (e.g., through a given side ofwaveguide 660, similar to side 360 c). Similarly, a second portion ofemitted light 604 could be reflected by mirror 652 and transmitted outof waveguide 660 at output end 660 c; a third portion of emitted light604 could be reflected by mirror 654 and transmitted out of waveguide660 at output end 660 d; and a fourth portion of emitted light 604 couldbe reflected by mirror 656 and transmitted out of waveguide 660 atoutput end 660 e.

Additionally, although not shown, system 600 may also include aplurality of apertures that at least partially overlap (along thez-axis) locations of output ends 660 b, 660 c, 660 d, 660 e, similarlyto the arrangement of apertures 420 a, 420 b, 420 c, 420 d shown in FIG.4B relative to output ends of waveguides 460, 462, 464, 466. Further,system 600 may also include a plurality of receivers (not shown) thatare co-aligned with the apertures (and thus with output ends 660 b, 660c, 660 d, 660 e) similarly to receivers 410, 412, 414, 416 of FIG. 4C.

Thus, waveguide 660 can be used to distribute the energy from emittedlight 604 into four different transmit paths that are co-aligned withreceive paths that overlap output ends 660 b, 660 c, 660 d, 660 e (e.g.,in the direction of the z-axis). To that end, for instance, light source640 can be used to drive four separate transmit channels of system 600using a single waveguide 660 instead of using four separate waveguides.

For example, waveguide 660 may extend lengthwise from input end 660 a tooutput ends 660 b, 660 c, 660 d, 660 e. Further, as shown, waveguide 660may include a first lengthwise portion ‘a’ that extends from input end660 a to a second lengthwise portion ‘b’ of waveguide 660; the secondlengthwise portion ‘b’ may extend from the first lengthwise portion ‘a’to a third lengthwise portion ‘c’ of waveguide 660; and the thirdlengthwise portion ‘c’ may extend from the second lengthwise portion ‘b’to output ends 660 b, 660 c, 660 d, 660 e.

Additionally, system 600 may include reflectors 690, 692 that arearranged along opposite sides of the first lengthwise portion ‘a’.Reflectors 690, 692 may be implemented as mirrors or other reflectivematerials that are configured to reflect wavelengths of emitted light604 incident thereon. To that end, a non-exhaustive list of examplereflective materials of reflectors 690, 692 includes gold, aluminum,other metal or metal oxide, synthetic polymers, hybrid pigments (e.g.,fibrous clays and dyes, etc.), among other examples.

In one embodiment, reflectors 690, 692 may include two parallel mirrorsthat are disposed on or adjacent to horizontal sides (e.g., along twoparallel x-z planes) of first waveguide portion ‘a’. In this embodiment,reflectors 690 and 692 may together provide a homogenizer for emittedlight 604 entering waveguide 660. For example, reflectors 690, 692 mayreflect emitted light 604 incident thereon (horizontally). As a result,the energy of emitted light 604 entering the second portion ‘b’ ofwaveguide 660 may be distributed more uniformly (i.e., homogenized)relative to the energy distribution of emitted light 604 at input end660. By doing so, for instance, the energy of emitted light 604 can bemore uniformly distributed among the transmit channels associated withoutput ends 660 b, 660 c, 660 d, 660 e.

In some embodiments, system 600 may additionally or alternativelyinclude reflectors disposed along other sides of waveguide 660 tohomogenize emitted light 604 vertically (e.g., along z-axis) as well ashorizontally (e.g., along y-axis). For example, two parallel reflectorscan be similarly arranged along two other sides of waveguide 660 (e.g.,sides that are parallel to the surface of the page) to homogenizeemitted light 604 vertically.

In some implementations, emitted light 604 can be homogenized in avariety of ways in addition to or instead of using reflectors 690 and692.

In a first implementation, system 600 may alternatively be configuredwithout reflectors 690 and 692. For example, waveguide portion ‘a’ canbe configured to have a sufficiently large length to allowhomogenization of emitted light 604 via total internal reflection evenwithout reflectors 690 and 692.

In a second implementation, one or more sides of waveguide 660 (e.g.,the sides on which reflectors 690 and 692 are shown to be disposedand/or one or more other sides of waveguide portion ‘a’) can bealternatively or additionally tapered (e.g., tapered in or tapered out)to achieve better homogeneity of emitted light 608 in a shorter distancefrom side 660 a to the second waveguide portion ‘b’ (e.g., shorterlength of waveguide portion ‘a’ than in an implementation where thesides are not tapered).

In a third implementation, system 600 may include one or more mirrorsthat fold the path of emitted light 604 to achieve improved homogeneityof emitted light 604 in a shorter distance from side 660 a to the secondwaveguide portion ‘b’ (e.g., shorter length of waveguide portion ‘a’than in an implementation where the one or more mirrors are notpresent). Other implementations for homogenizing emitted light 604 arepossible as well.

In some examples, as shown, a width of waveguide 660 in the secondlengthwise portion ‘b’ may gradually increase to control divergence(horizontally) of emitted light 604 that is guided inside the secondportion ‘b’ toward the third portion ‘c’. In this way, waveguide 660 canallow divergence of emitted light 604 (horizontally) before guidingrespective portions of the guided light toward output ends 660 b, 660 c,660 d, 660 e. To that end, a length of the second portion ‘b’ may beselected to sufficiently allow emitted light 604 from first waveguideportion ‘a’ to diverge horizontally (e.g., in the direction of they-axis) before being divided between the separate branches of waveguide660 in waveguide portion ‘c’.

In the third lengthwise portion ‘c’, waveguide 660 may include aplurality of elongate members (e.g., branches, etc.) that extend awayfrom one another to define separate transmit paths of respectiveportions of emitted light 604 toward output ends 660 b, 660 c, 660 d,660 e. In the example shown, waveguide 660 has four elongate members(e.g., branches, etc.). A first elongate member may correspond to theportion of waveguide 660 that extends from waveguide portion ‘b’ tooutput end 660 b; a second elongate member may correspond to the portionof waveguide 660 that extends from waveguide portion ‘b’ to output end660 c; a third elongate member may correspond to the portion ofwaveguide 660 that extends from waveguide portion ‘b’ to output end 660d; and a fourth elongate member may correspond to the portion ofwaveguide 660 that extends from waveguide portion ‘b’ to output end 660e.

With this arrangement, waveguide 660 may guide: a first portion ofemitted light 604 via the first elongate member toward end 660 b; asecond portion of emitted light 604 via the second elongate membertoward end 660 c; a third portion of emitted light 604 via the thirdelongate member toward end 660 d; and a fourth portion of emitted light604 via the fourth elongate member toward end 660 e. Further, forexample, the respective portions of emitted light 604 (guided via therespective elongate members) may then be reflected by mirrors 650, 652,654, 656 out of the page (e.g., in the direction of the z-axis) andtoward a scene.

Thus, with this arrangement, waveguide 660 may be configured as a beamsplitter that splits portions of emitted light 604 into several portionsthat are guided through a respective elongate member (e.g., branch) ofwaveguide 660 toward a respective output end. Alternatively oradditionally, in some implementations, an elongate member can extendtoward one or more additional elongate members (not shown) instead ofterminating at an output end. For example, the first elongate member(associated with output end 660 b) may split the guided light thereininto a plurality of branches (e.g., elongate members) that terminatewith several output ends instead of the single output end 660 b. Thus,in this example, waveguide 660 can separate light 604 (guided therein)into additional output ends to define additional transmit (and/orreceive) channels of system 600. Further, in some examples, each of theadditional branches extending from the first elongate member can besimilarly split to more branches, etc. Similarly, the second, third,and/or fourth elongate members (respectively associated with output ends660 c, 660 d, 660 e) can alternatively or additionally extend towardmultiple branches of waveguide 660 instead of terminating, respectively,at output ends 660 c, 660 d, 660 e.

Thus, it is noted that waveguide 660 is shown to have one input end andfour output ends only for the sake of example. Various alternativeimplementations of waveguide 660 are possible without departing from thescope of the present disclosure. In one example, fewer or more elongatemembers may extend from waveguide portion ‘b’. In another example, oneor more of the elongate members in waveguide portion ‘c’ can be splitinto multiple separate branches instead of terminating at a respectiveoutput end. Other examples are possible.

With any of these arrangements for example, waveguide 660 can thus beconfigured to drive multiple transmit channels using a same light source(e.g., light source 640). Further, in some examples, each of thetransmit channels defined by waveguide 660 may transmit a respectivelight pulse at a substantially similar time (e.g., in a grid pattern,etc.) toward an environment of system 600 (e.g., the respective lightpulses may originate from a single light pulse that was split bywaveguide 660).

In some implementations, a cross-sectional area of at least part of anelongate member of waveguide 660 may gradually decrease in a directionof propagation of the guided light therein. For example, as shown, thefirst elongate member may have a gradually decreasing cross-sectionalarea near output end 660 b. With this configuration, for instance, theangular spread of rays in the first portion of emitted light 604 exitingwaveguide 660 at output end 660 b may be larger than if there was notaper (i.e., gradually decreasing cross-sectional area) near output end660 b. Alternatively, in another embodiment, the taper near output end660 b can be in an opposite direction (e.g., gradually increasingcross-sectional area of the first elongate member near output 660 b). Inthis embodiment, the angular spread of rays in the first portion ofemitted light 604 exiting waveguide 660 at output 660 b may be smallerthan if there was no taper near output end 660 b. Thus, in someimplementations, system 600 can be configured to control the angularspread of rays in transmitted light signals by tapering side walls ofwaveguide 660. Through this process, for instance, the angular spread ofthe transmitted rays may be selected to match a numerical aperture of alens (not shown), such as any of lenses 130, 230, 330, 430, 530, and/or630 for instance, that directs the transmitted rays toward anenvironment of system 600.

As shown, the second, third, and fourth elongate members may also havegradually decreasing widths (e.g., walls of waveguide 660 tapered in)near respective output ends 660 c, 660 d, 660 e. However, in line withthe discussion above, the walls of waveguide 660 near output ends 660 c,660 d, 660 e, could alternatively be tapered out (e.g., graduallyincreasing cross-sectional areas, etc.) to otherwise control the angularspread of output light beams depending on the particular configuration(e.g., lens characteristics, etc.) of system 600.

It is noted that system 600 may include fewer, more, and/or differentcomponents than those shown. For example, although waveguide 660 isshown to include four elongate members that define four transmit pathsextending through four output ends 660 b, 660 c, 660 d, 660 e, waveguide660 may alternatively include fewer or more output ends (and associatedelongate members). In one embodiment, waveguide 660 may direct emittedlight 604 toward eight output ends. In this embodiment, a single lightsource 640 may drive eight separate transmit channels (co-aligned with 8corresponding receive channels) of system 600. Further, in thisembodiment, system 600 may include 32 waveguides coupled to 32 lightsources. Thus, in this embodiment, system 600 may define 32*8=256co-aligned transmit/receive channels that are driven using 32 lightsources (e.g., lasers, etc.). Other configurations are possible.

III. EXAMPLE METHODS AND COMPUTER READABLE MEDIA

FIG. 7 is a flowchart of a method 700, according to example embodiments.Method 700 presents an embodiment of a method that could be used withsystems 100, 290, 300, 400, 500, 600, and/or device 200, for example.Method 700 may include one or more operations, functions, or actions asillustrated by one or more of blocks 702-708. Although the blocks areillustrated in a sequential order, these blocks may in some instances beperformed in parallel, and/or in a different order than those describedherein. Also, the various blocks may be combined into fewer blocks,divided into additional blocks, and/or removed based upon the desiredimplementation.

In addition, for method 700 and other processes and methods disclosedherein, the flowchart shows functionality and operation of one possibleimplementation of present embodiments. In this regard, each block mayrepresent a module, a segment, a portion of a manufacturing or operationprocess, or a portion of program code, which includes one or moreinstructions executable by a processor for implementing specific logicalfunctions or steps in the process. The program code may be stored on anytype of computer readable medium, for example, such as a storage deviceincluding a disk or hard drive. The computer readable medium may includea non-transitory computer readable medium, for example, such ascomputer-readable media that stores data for short periods of time likeregister memory, processor cache and Random Access Memory (RAM). Thecomputer readable medium may also include non-transitory media, such assecondary or persistent long term storage, like read only memory (ROM),optical or magnetic disks, compact-disc read only memory (CD-ROM), forexample. The computer readable media may also be any other volatile ornon-volatile storage systems. The computer readable medium may beconsidered a computer readable storage medium, for example, or atangible storage device. In addition, for method 700 and other processesand methods disclosed herein, each block in FIG. 7 may representcircuitry that is wired to perform the specific logical functions in theprocess.

At block 702, method 700 involves emitting (e.g., via light source 340)light (e.g., 304) toward a first side (e.g., 360 a) of a waveguide(e.g., 360). At block 704, method 700 involves guiding, inside thewaveguide, the emitted light from the first side to a second side (e.g.,360 b) of the waveguide opposite the first side. At block 706, method700 involves reflecting (e.g., via mirror 350) the guided light toward athird side (e.g., 360 c) of the waveguide. In some examples, at least aportion of the reflected light may propagate out of the third sidetoward a scene. Referring back to FIGS. 3A and 3B for example, reflectedlight 304 may propagate through aperture 320 a and lens 330 toward thescene (e.g., object 398). At block 708, method 700 involves focusing,via a lens (e.g., 330), light (e.g., 302) propagating from the sceneonto the waveguide and a light detector (e.g., any of the lightdetectors included in array 310, etc.).

IV. CONCLUSION

The above detailed description describes various features and functionsof the disclosed systems, devices, and methods with reference to theaccompanying figures. While various aspects and embodiments have beendisclosed herein, other aspects and embodiments will be apparent. Thevarious aspects and embodiments disclosed herein are for purposes ofillustration only and are not intended to be limiting, with the truescope being indicated by the following claims.

What is claimed:
 1. A system comprising: a light source that emitslight; a waveguide that guides the emitted light from a first side ofthe waveguide toward a second side of the waveguide opposite the firstside, wherein the waveguide has a third side extending between the firstside and the second side; a mirror that reflects the guided light towardthe third side of the waveguide, wherein at least a portion of thereflected light propagates out of the waveguide toward a scene; a lightdetector; and a lens that focuses light from the scene toward thewaveguide and the light detector, wherein at least a portion of thefocused light propagates from the lens to the light detector withoutpropagating through the waveguide.
 2. The system of claim 1, wherein thelens focuses a first portion of the focused light onto the waveguide anda second portion of the focused light adjacent to the waveguide, whereinthe waveguide is at a first distance to the lens, and wherein the lightdetector is at a second distance to the lens.
 3. The system of claim 1,further comprising an opaque material that defines an aperture, whereinat least a portion of the focused light is transmitted through theaperture toward the light detector.
 4. The system of claim 3, whereinthe opaque material is interposed between the lens and the waveguide,and wherein the at least portion of the reflected light propagatesthrough the aperture toward the scene.
 5. The system of claim 3, whereinthe opaque material is interposed between the waveguide and the lightdetector.
 6. The system of claim 1, wherein the mirror is at a firstangle to the third side of the waveguide, wherein the first side of thewaveguide is at a second angle to the third side of the waveguide, andwherein the first angle is less than the second angle.
 7. The system ofclaim 1, wherein the second side of the waveguide is tilted toward thethird side, and wherein the mirror is disposed on the second side. 8.The system of claim 1, further comprising: a first substrate, whereinthe third side of the waveguide is disposed on the first substrate; asecond substrate; and a given material disposed between the firstsubstrate and the second substrate, wherein the given material is incontact with the first substrate, the second substrate, and thewaveguide, and wherein the waveguide has an index of refraction greaterthan a given index of refraction of the given material.
 9. The system ofclaim 8, wherein the waveguide comprises a photoresist, and wherein thegiven material comprises an adhesive that couples the first substrate tothe second substrate.
 10. The system of claim 1, further comprising: alight filter disposed between the waveguide and the light detector,wherein the light filter attenuates light propagating toward the lightdetector.
 11. A system comprising: a light source that emits light; awaveguide having an input end and one or more output ends opposite theinput end, wherein the waveguide guides the emitted light from the inputend to the one or more output ends, and wherein the waveguide has agiven side that extends from the input end to the one or more outputends; one or more mirrors that reflect at least a portion of the guidedlight toward the given side of the waveguide, wherein the reflectedlight propagates out of the waveguide; a lens that directs, toward ascene, the reflected light propagating out of the waveguide; an opaquematerial that defines a plurality of apertures including at least afirst aperture and a second aperture; a first array of light detectors;and a second array of light detectors, wherein the lens focuses lightfrom the scene toward the waveguide and the first and second arrays oflight detectors, wherein the lens focuses a first portion of the focusedlight into the first aperture and the first portion of the focused lightpropagates toward the first array of light detectors via the firstaperture, and wherein the lens focuses a second portion of the focusedlight into the second aperture and the second portion of the focusedlight propagates toward the second array of light detectors via thesecond aperture.
 12. The system of claim 11, wherein the one or moreoutput ends include at least a first end and a second end, wherein thewaveguide comprises a plurality of elongate members including at least afirst elongate member and a second elongate member, wherein the firstelongate member guides a first portion of the emitted light toward thefirst end, and wherein the second elongate member guides a secondportion of the emitted light toward the second end.
 13. The system ofclaim 12, wherein the one or more mirrors include at least a firstmirror and a second mirror, and wherein the waveguide guides the firstportion of the emitted light toward the first mirror via the firstelongate member and the second portion of the emitted light toward thesecond mirror via the second elongate member.
 14. The system of claim12, wherein a cross-sectional area of at least a portion of the firstelongate member gradually decreases in a direction of propagation of thefirst portion of the emitted light guided inside the first elongatemember.
 15. The system of claim 11, wherein the one or more mirrorsreflect a first portion of the emitted light toward the first apertureand a second portion of the emitted light toward the second aperture.16. The system of claim 11, further comprising: one or more reflectors,wherein the waveguide extends lengthwise from the input end to the oneor more output ends, and wherein the one or more reflectors are disposedon a lengthwise portion of the waveguide.
 17. The system of claim 16,wherein the lengthwise portion of the waveguide is adjacent to the inputend, and wherein the one or more reflectors are disposed along at leasttwo opposite sides of the lengthwise portion of the waveguide.